I love the pre-lift. It kinda throws you off a bit. The new trains also help with this ride a lot, not only in the barrel roll, but the rest of the ride also. And it's awesome that they turned on the lights in the tunnel so that you can see. Advantages of test run videos!
They could've use all wood but it would've required a ton of it and that would've looked horrible. Besides, Hades was initially built as a hybrid (steel structure with wood trackbed) so it only makes sense to use that for the inversion.